Acid-settable liquids are known and used in the art. Usually the liquid and a suitable acid are mixed and the liquid sets, gels or polymerizes. In the ordinary case the timing of the setting depends upon a precise adjustment of the acid concentration, and effective mixing of the reactants, otherwise the desired setting may occur too soon, only after a long time or not at all. In general, a treatment of an oil well by the introduction of a homogeneous mixture of an acid and an acid-settable liquid into a zone or formation adjacent to a well bore is relatively unsatisfactory because of the lack of practical control of the time factor. One proposal (U.S. Pat. No. 3,537,522) has been to introduce a mixture of an acid-releasing (AR) compound and a acid-settable liquid into a formation containing water. The interaction of the formation water and the AR compound is expected to produce the acid required to catalyse the desired setting of the liquid. Included among the disadvantages of this proposal is the limitation that it is only useful for a water containing formation, and it is subject to the vagaries as to the amount of water available in a formation, the adequacy of the mixing of the water and acid-settable liquid, and the like. In general, methods which require the introduction of acid-setting reaction components into a formation in stages are unsatisfactory in the absence of positive control means, effective mechanical mixing and the like, and these means are, in general, not available in many circumstances, for example in an earthen formation or zone, or in the treatment of a zone adjacent to a well bore. Other disadvantages experienced in the use, as known in the art, of acid-settable liquids for the treatment of earthen formations or zones include:
1. the problem of keeping the reactants separated until the desired encounter in the formation: PA1 2. the problem of obtaining a timely encounter of the acid and acid-settable fluid in the formation; PA1 3. the problem with flash-setting fluids such as furfuryl alcohol and the like in view of their extreme sensitivity to local fluctuation in pH; and PA1 4. the relatively inefficient utilization of the reagents due to incomplete mixing of the fluid and catalyst in the formation. PA1 1. it provides effective delay and control of the timing of the desired catalytic action; PA1 2. it permits the introduction of an acid-settable liquid and the catalyst system as a unit into the subterranean zone as a one-stage operation; PA1 3. it provides a method which can be used over a wide range of temperatures, particularly the elevated temperatures frequently encountered in subterranean zones; PA1 4. in a particular embodiment it provides a catalyst system which can be prepared in advance, stored and conveniently transported to the field; and PA1 5. it has other advantages which will become evident in the description to follow. PA1 1. an acid-settable hydroxylic liquid; PA1 2. a nonhydroxylic acid-settable liquid which contains at least an effective amount of a hydroxylic acid-settable liquid; or PA1 3. a nonhydroxylic acid-settable liquid which contains an effective amount of: PA1 1. the particular acid-releasing compound(s) chosen; PA1 2. the base or bases employed; PA1 3. the relative amounts of (1) and (2) employed; and PA1 4. the polarity (dipole moment) of the liquid acid-settable mixture. PA1 1. the compound of itself (prior to solvolysis) exhibits a substantially neutral pH, i.e., about 7 in aqueous ethanol at 18.degree.C.; PA1 2. the solvolysis rate (acid-releasing rate) of the compound is within the required range for suitable pH control; and PA1 3. the compound is sufficiently soluble in the acid-settable liquid to provide the strong acid needed to reduce the pH to the required level. PA1 1. the solubility of the base in the acid-settable fluid; and PA1 2. the pH which should be maintained prior to the drop to the level required for catalysis.